Photometric Observation and Study of the Transiting Exoplanetary System HAT-P-8

Three transit events of HAT-P-8 were observed by using the 1 m telescope of Yunnan Observatory and the 2.4 m telescope of Lijiang Astronomical Station in 2009 and 2012, respectively. The observational data are reduced with the coarse de-correlation and SysRem algorithms in order to improve the signal to noise ratio of the transit signals. The MCMC (Markov Chain Monte Carlo) technique is applied to analyzing the three transit light curves simultaneously, then the new parameters of the HAT-P-8 system are derived. The new value of the radius of HAT-P-8b is smaller than that given by Latham et al., while it is consistent with the value derived recently by Mancini et al. By linear fitting on the 23 high-precision mid-transit times, the orbital period of HAT-P-8b is refined as P =3.0763461±0.0000021 d, and from the (O − C) analysis no obvious TTV (Transit Timing Variation) signal has been detected.